President Obama vowed yesterday to join Planned Parenthood in fighting against what he said are efforts by states to turn women’s health back to the 1950s, before the Supreme Court legalized abortion nationwide, and singled out the GOP-governed states of North Dakota and Mississippi for criticism.

“When politicians try to turn Planned Parenthood into a punching bag, they’re not just talking about you,” Obama said, becoming the first sitting president to address the abortion rights group in person. “They’re talking about the millions of women who you serve.”

Obama asserted that “an assault on women’s rights” is under way across the country, with bills introduced in more than 40 states to limit or ban abortion or restrict access to birth control or other services.

“The fact is, after decades of progress, there’s still those who want to turn back the clock to policies more suited to the 1950s than the 21st century,” he said. “And they’ve been involved in an orchestrated and historic effort to roll back basic rights when it comes to women’s health.”

Last month, North Dakota Republican Gov. Jack Dalrymple signed a law that bans abortions as early as six weeks, or when a fetal heartbeat is detected, making the state the most restrictive in the nation in which to get the procedure.

Obama said “a woman may not even know that she’s pregnant at six weeks.”

More than a year ago in Mississippi, a “personhood” ballot initiative that would have defined life as beginning at fertilization was defeated by 58 percent of voters in November 2011, the same election in which staunch abortion opponent Phil Bryant, a Republican, was elected governor. Bryant had campaigned for the initiative. Abortion opponents are expected to soon begin a signature drive to get a similar initiative on the ballot in 2014 or 2015.

“Mississippi’s a conservative state, but they wanted to make clear there’s nothing conservative about the government injecting itself into decisions best made between a woman and her doctor,” Obama said of the voters there.

The president lauded Planned Parenthood’s nearly 100 years of providing cancer screenings, contraception and other health services for women and assured those fighting to protect abortion rights that they have an ally in him.

“You’ve also got a president who’s going to be right there with you, fighting every step of the way,” Obama said.

In North Dakota, Republican state Rep. Bette Grande, an abortion opponent from Fargo who introduced the bill banning most abortions based on a fetal heartbeat, said she was happy Obama took notice of her state’s stance on the issue.